Looks like Mix09 (March 18-20) is the stage where Microsoft will reveal details of Silverlight 3 (is it really 3 already?). On the session list is:
What’s new in Silverlight 3 (Joe Stegman)
What’s new in Silverlight 3 media (Larry Olson)
Deep Dive into Silverlight graphics – come hear about the Silverlight 3 rendering pipeline (Seema Ramchandani, Marshall Agnew)